1. Field of Use
This invention relates generally to excavating machines, such as hydraulic mining shovels or the like, and in particular to attachment means for the shovel.
2. Description of the Prior Art
In large excavating machines, such as hydraulic mining shovels or the like, the attachment means for the shovel are designed to enable the shovel to be movable through a wide range of positions while excavating, handling and unloading heavy loads of overburden, ore or the like. Maximum desirable shovel movement and articulation require the attachment means to employ numerous pivotably movable interconnected components, such as arms, links and beams, and, in some instances, one or more extendable and retractable hydraulic cylinders or rams which effect movement of other components, as well as serving a supporting function. In some prior art machines, the shovel attachment means are designed in such a manner that some components are subject to undesirable bending stresses either continually or at least whenever certain operating functions are performed. Such stresses can shorten the life of the component or its pivot pin and bearing means, thereby creating possible danger to men and equipment during operation and also necessitating costly repairs and downtime. Very often design requirements of a particular machine necessitate a trade-off between functional requirements and acceptable stress factors. Typically, a bending moment occurs in a beam when a load and a reactive force (such as is imposed by a hydraulic cylinder) are imposed in the same direction on opposite sides of a beam pivot point.
The prior art discloses excavating and material handling machines of many types wherein various components in the shovel attachment means are subjected to bending moments. See, for example, U.S. Pat. Nos. 3,990,161; 3,491,906; and 3,370,729; German Pat. Nos. 2,136,007 and 2,011,262; and Australian Pat. No. 401,738.